Low Field Nuclear Magnetic Resonance (LF-NMR) and zero-field NMR, also known as Nuclear Quadrupole Resonance, are used for detecting and characterizing materials using radio frequency (RF) spectroscopy, as well as for imaging applications such as magnetic resonance imaging (MRI). Typically, low field and zero field measurements have lower signal to noise levels than are achievable in traditional, high field NMR and MRI, but can be used to detect different properties, including some which have security applications, such as the spectroscopic fingerprints of different explosives, and potentially some nuclear and biological materials as well. In addition, the low-field techniques eliminate the need for large superconducting magnets as in traditional high field NMR and MRI. This allows low-field and zero-field NMR systems potentially to be more portable, miniaturizable, and lower power.
Atomic magnetometers have been shown in previously published work to offer a signal to noise advantage in detecting RF fields over pick-up coils at frequencies below 5 megahertz (MHz). They also offer an advantage in terms of portability and expense over other detector alternatives, such as Superconducting Quantum Interference Device (SQUID) magnetometers, which require cryogenic cooling. However, existing RF-sensitive atomic magnetometers are still relatively bulky devices, and the geometry of the interactions between the laser fields and the atomic vapor limits prospects for miniaturization. For applications in which size, weight, and power are restricted, neither existing atomic magnetometers nor SQUIDS provide an adequate solution.